console.log({}.valueOf());//{}
console.log({}.toString());//[object Object]
console.log([].valueOf());//[]
console.log([].toString());//""

console.log(isNaN(NaN));//true

console.log(parseFloat('0xA') === 0);

const arr1=[,,,,,]
const arr2=new Array(5)
const arr3=new Array("","","","","")
console.log(arr1.length,arr2.length,arr3.length);